Conventionally, in portable information devices such as notebook personal computers, a high-frequency antenna has been disposed on the upper end of the monitor thereof so as to attain equal characteristics on both the display side and back sides thereof regardless of whether the monitor is opened or not. Further, the antenna portion is so arranged as not to project from the face of the monitor to give design consideration thereto.
However, unlike notebook personal computers, the monitors of integrated car navigation/audio systems do not have a sufficient free space in the monitor portion thereof. Therefore, the antenna has been disposed in the narrow free space thereof, and it is difficult to satisfy the antenna characteristics thereof. In particular, it is usual for an integrated car navigation/audio system to be provided by being fastened to a center console, and for the monitor portion thereof to be opened and closed for taking out the disk. In this respect, integrated car navigation/audio systems are significantly different from notebook personal computers.
(See patent documents 1 and 2, for example.)
    Patent document 1: JP-A-2000-172376 (page 4, FIG. 1)    Patent document 2: JP-A-2004-5653 (page 4, FIGS. 1 to 3)
The conventional display device is arranged as mentioned above. As a result, it is necessary that the antenna portion thereof be disposed at a location where there is no obstacle and where the antenna can have a good reception. There is a problem that a high-frequency antenna particularly requires a sufficient free space because of its susceptibility to the interference of peripheral sheet-metal parts.
The present invention has been accomplished to solve the above-mentioned problem. An object of the present invention is to provide a display device capable of meeting limiting conditions for installing the antenna and attaining excellent transmit-receive characteristics even when the antenna is installed at a narrow mounting space.